This invention relates to extremely low viscosity adducts of lactams with monofunctional or polyfunctional aliphatic, cycloaliphatic or araliphatic alcohols and mercaptans, to a process for their production and to the use of this new class of compounds as, for example, highly active solvents for compounds that are difficult to dissolve.
The new adducts contain 1 mol of such monofunctional or polyfunctional alcohol or mercaptan per mol of lactam.
It has already been proposed to use molten .epsilon.-caprolactam (70.degree.C) as a solvent for substantially insoluble, relatively high molecular weight substances, for example polymethylene thioureas, optionally in conjunction with inert organic solvents free from hydroxyl groups, such as aromatic hydrocarbons, acetone, ethers, esters, tetrahydrofuran and aliphatic halohydrocarbons as solvents (H. Staudinger and K. Wagner, German Pat. No. 910,336). Disadvantages of this solvent, or of the aforementioned mixtures, include the relatively high melting point of .epsilon.-caprolactam, and the very marked tendency of caprolactam to crystallise at temperatures below 70.degree.C with the result that it is impossible to prepare solutions which are storage-stable, especially at room temperature and at temperatures below room temperature.